From Nookipedia, the Animal Crossing wiki
summer in Animal Crossing, Summer Campers may set up tents in the player's village, on top of signposts. The campers are not from the player's village, unlike the builders of igloos.
When the public works project the Campsite has been built in the town, villagers from out of town may put up their tent on the towns' Campsite. The villager may play a game in which the player can obtain regular or Camping Gear from the villager or sell one of their items (excluding rare items such as the silver and golden tools) for the amount of bells determined. The Camping Gear cannot be found anywhere else, but can be reordered from the catalog at Timmy and Tommy's Store however. The player may also be asked to play a game to determine if the animal moves into town, but this will only happen if the town currently has fewer than ten villagers living there.